Fix potential memory leak issue when using llvm::EngineBuilder().selectTarget()
Fix issue of accessing aot_value's fields after it is freed
Fix JIT not print failed to link import warning
Change some error messages: 'fail to' to 'failed to'
Update error message when SIMD isn't enabled
Fix install littlevgl wasm app of wasi version failed
Signed-off-by: Wenyong Huang <wenyong.huang@intel.com>